Before the parent's edit it was about line length limits, IIRC. In any case that's what my comment was referring to. If you want to limit line length to, say, 100 characters (to visually fit within a 100-character wide window or terminal), then it matters what tab width you use. If you check it assuming a tab width of 8, someone working with a tab width of 2 will be limited to shorter lines the deeper the indentation level. Conversely, when the check assumes a tab width of 2, someone working with a tab width of 8 is likely to see lines longer than 100 characters although the lines passed the check.